Wear resistant coating composition and filler pack therefor

Abstract

The invention provides a coating composition and a filler package for the coating composition. In an embodiment, the coating composition includes a hydroxyl functional resin having a plurality of free hydroxyl groups, a crosslinking agent having hydroxyl reactive functional groups, a solvent, an inorganic particulate component, and a wax powder. The inorganic particle component has a D90 nominal particle size of from about 12 [mu] m to about 22 [mu] m as determined using a screen according to ASTM 5861-07 (2017).

Description

TECHNICAL FIELD

[0001] Generally, the present disclosure relates to a coating composition and a filler package for the coating composition. More specifically, the present disclosure relates to a coating composition having abrasion resistance after curing and a filler package for the coating composition. BACKGROUND

[0002] Coating compositions are used for a variety of applications, including household cabinets and appliances, automotive refinish, building materials, and industrial applications. The coating compositions are applied to a substrate to form a film or coating on one or more surfaces of the substrate after curing. The coating compositions can provide a range of benefits when applied to a substrate. For example, the coating can impart color or other aesthetic properties, and / or provide protection from certain chemicals or environmental conditions.

[0003] For many consumer products, particularly cabinets, consumers have long valued properties of the coating such as durability, long-lasting color, chip and flake resistance, and stain and cleaning product resistance. In recent years, there has been an increasing demand for abrasion resistant (such as mar and scratch) coatings. Current coating compositions used for articles that can be subjected to abrasion often fail to meet customer specifications for abrasion resistance without compromising other properties.

[0004] The use of additives in coating compositions to improve the properties of the resulting cured film, such as hardness, is known in the art. However, known additives can not sufficiently improve the hardness or other physical properties to meet customer requirements for abrasion resistance. Known additives can also result in a decrease in other important properties of the coating composition, making it difficult to handle and apply the coating composition by existing application methods, such as spraying or brushing.

[0005] Accordingly, it would be desirable to provide a coating composition and a filler package for the coating composition that can be efficiently applied using existing application equipment and forms a film having the highest abrasion resistance after curing. Moreover, in view of the background art, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the foregoing technical field. SUMMARY

[0006] This summary is intended to introduce some concepts, which will be further described below in the detailed description. This summary is not intended to be determined as key or essential features of the claimed subject matter, nor is it intended to be used to assist in determining the scope of the claimed subject matter.

[0007] Provided herein are coating compositions, filler packages for use in the coating compositions, composite articles comprising films formed from the coating compositions, and methods of forming composite articles. In one embodiment, a coating composition comprises a hydroxyl-functional resin having a plurality of free hydroxyl groups, a crosslinker having a hydroxyl-reactive functional group, a solvent, an inorganic particulate component, and a wax powder. The inorganic particulate component has a D90 nominal particle size of about 12 microns to about 22 microns as measured using a sieve according to ASTM 5861-07 (2017).

[0008] In another embodiment, a filler package comprises an inorganic particulate component and a wax powder. The inorganic particulate component has a hardness value on the Mohs hardness scale of about 4 to about 8 and a D90 nominal particle size of about 12 microns to about 22 microns as measured using a sieve according to ASTM 5861-07 (2017). The wax powder has a softening point of about 150 °C to about 180 °C and an average nominal particle size of about 20 microns to about 25 microns as measured using a sieve according to ASTM 5861-07 (2017). DETAILED DESCRIPTION

[0009] The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of it. Furthermore, the application is not intended to be limited by any of the foregoing description, or the following examples, which are included for illustrative purposes only.

[0010] Provided herein are coating compositions and filler packages for use in the coating compositions. The coating compositions can be effectively handled and applied using conventional application equipment and, upon curing to a film, exhibit maximum abrasion resistance (such as mar and scratch). It has been discovered that the addition of a filler package comprising both an inorganic particulate component and a wax powder to a coating composition comprising a hydroxyl-functional resin having a plurality of free hydroxyl groups, a crosslinker having a hydroxyl-reactive functional group, and a solvent improves the abrasion resistance of the coating to meet customer requirements while not affecting the handleability and application of the coating composition, the inorganic particulate component having a D90 nominal particle size of about 12 microns to about 22 microns as measured using a sieve according to ASTM 5861-07 (2017).

[0011] The term "about" as used herein, unless otherwise indicated or otherwise apparent from context, is understood in the normal range of tolerances for a given measurement using standard measuring equipment, for example within the mean ± 2 standard deviations for a particular measuring equipment. "About" can be understood to be within ± 10%, 5%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the indicated value. "About" can also be understood to imply the recited exact value. Unless otherwise clear from context, all numerical values provided herein are modified by the term "about."

[0012] As used herein, "abrasion" refers to physical damage or injury to the surface of an object. Abrasion can include scratching, scuffing, wear, and / or other similar marks. The abrasion can be the result of long-term wear, or the abrasion can be caused by a discrete event, such as a forceful rubbing or scratching against another object.

[0013] As used herein, "nominal size" refers to a reference size of a particle. If the particle is spherical, the nominal size is defined as the diameter of the spherical particle. If the particle is not spherical, the nominal size is defined as the largest dimension of the particle.

[0014] As used herein, "average nominal particle size" or "D50 nominal particle size" refers to a measurement such that 50% by volume of the particles in the population have a nominal size less than the measurement. As used herein, "D90 nominal particle size" refers to a measurement such that 90% by volume of the particles in the population have a nominal size less than the measurement. As described herein, both the D50 and D90 nominal particle sizes are determined according to ASTM 5861-07 (2017) using a sieve.

[0015] The coating compositions provided herein include a hydroxyl-functional resin having a plurality of free hydroxyl groups; a crosslinker having a hydroxyl-reactive functional group; a solvent; an inorganic particulate component having a D90 nominal particle size of about 12 microns to about 22 microns as determined according to ASTM 5861-07 (2017) using a sieve; and a wax powder.

[0016] The hydroxyl-functional resin having a plurality of free hydroxyl groups is one of two components in the coating composition that react after curing to form a substantially crosslinked thermoset polymer film. The free hydroxyl groups in the hydroxyl-functional resin are capable of reacting under certain conditions to form crosslinks. Crosslinking aids in the curing of the coating composition to form a coating.

[0017] In some embodiments, the hydroxyl-functional resin can have a weight average molecular weight of about 6,000 Daltons to about 30,000 Daltons, as determined by gel permeation chromatography (GPC). In some embodiments, the hydroxyl-functional resin can have a glass transition temperature (Tg) of about 10 °C to about 60 °C. As used herein, “glass transition temperature” (Tg) is defined as the temperature at which a peak appears on a differential scanning calorimetry (DSC) curve when measured at a scan rate of 10 °C / minute. In some embodiments, the hydroxyl-functional resin can have a hydroxyl value of about 50 mg KOH / g to about 150 mg KOH / g, or alternatively about 140 mg KOH / g to about 190 mg KOH / g. As used herein, “hydroxyl value,” which can also be referred to as “OH number” or “OH value,” refers to the mass of potassium hydroxide (KOH) in milligrams required to neutralize the acetic acid produced from one gram of a chemical substance containing free hydroxyl groups after acetylation. As used herein, the hydroxyl value is analyzed by titration according to standard test method ASTM D4274-11.

[0018] In some embodiments, the hydroxyl-functional resin is selected from an acrylic resin, an alkyd resin, a polyester resin, a hydroxyl-functional polyepoxy resin, a polyester urea resin, a urea formaldehyde resin, or a combination thereof. Examples of acrylic resins include linear, branched, grafted, and / or block polyacrylates or polymethacrylates. Examples of polyesters include polyurethanes and branched co-polyesters. In some embodiments, the hydroxyl-functional resin includes an oligomer. In some embodiments, the hydroxyl-functional resin includes an acrylic alkyd resin, which is relatively easy to sand, but has other desirable properties, including resistance to moisture and chemicals, resistance to radiation, adhesion, flexibility, resistance to yellowing, and fast drying.

[0019] In some embodiments, the hydroxyl-functional resin is present in an amount of about 5 wt% to about 50 wt%, or about 7 wt% to about 35 wt%, or about 7 wt% to about 30 wt%, or about 10 wt% to about 28 wt%, based on the total weight of the coating composition.

[0020] A crosslinker having a hydroxyl-reactive functionality is included in the coating composition to facilitate crosslinking of the hydroxyl-functional resin. In some embodiments, the crosslinker has one hydroxyl-reactive functionality. In some embodiments, the crosslinker has two or more hydroxyl-reactive functionalities. In some embodiments, the crosslinker has an equivalent weight of about 25 grams / equivalent to about 250 grams / equivalent, or about 50 grams / equivalent to about 100 grams / equivalent. As used herein, "equivalent weight" refers to the mass of a crosslinker containing one equivalent of a reactive functionality (i.e., the molar mass of the crosslinker divided by the number of reactive functionalities per molecule of the crosslinker). In some embodiments, the crosslinker is selected from the group consisting of polyisocyanates, blocked polyisocyanates, melamine, melamine derivatives, benzoguanamine, silanes, epoxides, and combinations thereof. One example of a melamine derivative is alkylated melamine. In some embodiments, the crosslinker is a melamine-formaldehyde resin.

[0021] In some embodiments, the crosslinker is present in an amount of about 0.5 wt% to about 30 wt%, or about 1 wt% to about 25 wt%, or about 2 wt% to about 21 wt%, or about 4 wt% to about 10 wt%, based on the total weight of the coating composition.

[0022] In some embodiments, the coating composition is a one-component (lk) composition. As used herein, "one-component (lk) composition" is defined as a single-package system in which all of the ingredients of the coating composition are contained in one package, and the coating composition cures under certain conditions. When the one-component (lk) coating composition is stored in a can or other closed container, the hydroxyl-reactive functionality of the crosslinker does not react with the free hydroxyl groups in the hydroxyl-functional resin. This allows the coating composition to remain in the can without curing. However, when exposed to certain conditions, including heat, the hydroxyl-reactive functionality of the crosslinker reacts with the free hydroxyl groups in the hydroxyl-functional resin, resulting in crosslinking of the resin and curing of the coating composition to form a film. In some embodiments, the coating composition is a two-component (2k) composition. As used herein, "2k composition" is defined as a two-package system in which the ingredients of the coating composition are contained in two separate packages, and the two packages are combined together prior to application of the coating composition, and the coating composition cures upon combination and / or exposure to certain conditions.

[0023] Solvents are added to the coating composition for various purposes. For example, solvents can facilitate dissolution of other ingredients in the coating composition, help control the dynamic viscosity of the coating composition, improve adhesion of the coating to a substrate, and / or help improve the stability and shelf life of the coating composition. The coating composition can include only one solvent, or, the coating composition can include more than one solvent.

[0024] The solvent can be an organic solvent or an aqueous solvent. An example of an aqueous solvent is water. Examples of organic solvents include acetone, alcohols such as isopropyl alcohol or isobutyl alcohol, ketones such as methyl amyl ketone or methyl isobutyl ketone, acetates such as ethyl butyrate or propylene glycol monomethyl ether acetate, and aromatic or aliphatic hydrocarbon solvents. The solvent can be polar or non-polar. The appropriate type of solvent can be selected based on the properties of other ingredients present in the coating composition.

[0025] In some embodiments, the solvent is present in an amount of about 10 wt% to about 80 wt%, or about 20 wt% to about 70 wt%, or about 30 wt% to about 60 wt%, or about 40 wt% to about 50 wt%, based on the total weight of the coating composition.

[0026] Provided herein is a filler package that can be added to a coating composition. The filler package includes an inorganic particulate component and a wax powder. The inorganic particulate component has a D90 nominal particle size of about 12 microns to about 22 microns, as measured using a sieve according to ASTM 5861-07 (2017). When combined with a coating composition or ingredients of a coating composition, the filler package can improve the abrasion resistance of the resulting coating composition after curing into a film without compromising other properties of the coating composition.

[0027] An inorganic particulate component is included in the coating composition to improve the abrasion resistance of the coating composition after curing. The inorganic particulate component has a D90 nominal particle size of about 12 microns to about 22 microns, or about 12 microns to about 20 microns, or about 12 microns to about 18 microns, or about 12 microns to about 15 microns, as determined using a sieve according to ASTM 5861-07 (2017). It has been found that inorganic particulate components having a D90 nominal particle size of about 12 microns to about 22 microns help improve the abrasion resistance of the coating composition after curing into a film without creating undesirable surface texture in the film.

[0028] The inorganic particulate component can include particles having various shapes. For example, the particles can have a spherical shape, a spheroid shape, a cylindrical shape, a geometric shape, or an irregular shape. In some embodiments, the inorganic particulate component includes particles that all have the same overall shape. In some embodiments, the inorganic particulate component can have a hardness value on the Mohs hardness scale of about 4 to about 8, or about 4 to about 7, or about 5 to about 8, or about 5 to about 7.

[0029] In some embodiments, the inorganic particulate component includes metal silicate particles, tungsten carbide particles, calcium phosphate particles, magnesium oxide particles, barium titanate particles, or combinations thereof. For example, the metal silicate particles can include aluminum silicate, magnesium silicate, zirconium silicate, or combinations thereof. In some embodiments, the inorganic particulate component includes silicon dioxide (Si02) particles. The silicon dioxide particles can be coated with a metal such as silver or other material.

[0030] In some embodiments, the inorganic particulate component is present in an amount of about 0.1 wt% to about 5.0 wt%, or about 0.5 wt% to about 4.0 wt%, or about 0.5 wt% to about 2.0 wt%, based on the total weight of the coating composition.

[0031] A wax powder is included in the coating composition to improve the abrasion resistance of the cured coating composition. The wax powder can also help maintain the desired flowability of the coating composition. As used herein, "wax" refers to an organic compound. Within the coating composition, the wax powder is present in the form of a separate phase that is separate from the hydroxyl functional resin, the crosslinker, and any reaction products of the hydroxyl functional resin and the crosslinker that can be present.

[0032] In some embodiments, the average nominal particle size of the wax powder is about 10 microns to about 30 microns, or about 10 microns to about 25 microns, or about 20 microns to about 25 microns, as determined using a sieve mesh determination according to ASTM 5861-07(2017). In some embodiments, the softening point of the wax powder is about 100 °C to about 200 °C, or about 140 °C to about 190 °C, or about 150 °C to about 180 °C. As used herein, the "softening point" of a polymer refers to the ring and ball softening point as determined according to ASTM E28.

[0033] In some embodiments, the wax powder can include a natural wax, or the wax powder can also include a synthetic wax. In some embodiments, the wax powder can include long chain aliphatic hydrocarbons. In some embodiments, the wax powder can include functional groups such as fatty acids, primary and secondary alcohols, ketones, aldehydes, and fatty acid esters. In some embodiments, the wax powder includes polyethylene, polypropylene, polyamide, polytetrafluoroethylene, or combinations thereof. The wax powder particles include the above components in an amount of at least 95 wt%, or at least 99 wt%, based on the total weight of the particles.

[0034] In some embodiments, the wax powder is present in an amount of about 0.1 wt% to about 5.0 wt%, or about 0.5 wt% to about 4.0 wt%, or about 1.0 wt% to about 3.0 wt%, based on the total weight of the coating composition.

[0035] In some embodiments, the coating composition further comprises an acid catalyst. An acid catalyst can be included in the coating composition to accelerate the reaction of the hydroxyl-functional resin and the crosslinker during curing of the coating composition. The presence of an acid catalyst can be particularly advantageous when the crosslinker is melamine. In some embodiments, the acid catalyst is hydrophobic. In some embodiments, the acid catalyst comprises a sulfonic acid, a phosphoric acid, a benzoic acid, or a combination thereof. Examples of sulfonic acids include aromatic sulfonic acids such as dodecylbenzenesulfonic acid, p-toluenesulfonic acid, and dinonylnaphthalenesulfonic acid. The acid catalyst can be unblocked, or can be blocked with an amine such as dimethyl oxazolidine, 2-amino-2-methyl-l-propanol, N,N-dimethylethanolamine, or a combination thereof. The acid catalyst can be present in a catalytically active amount. In some embodiments, the acid catalyst can be present in an amount of about 0.1 wt% to about 10 wt%, or about 1.0 wt% to about 9.0 wt%, or about 3.0 wt% to about 8.0 wt%, based on the total weight of the coating composition.

[0036] In some embodiments, the coating composition further comprises a pigment. The pigment can be different in hardness and / or particle size from the inorganic particulate component. The pigment can be included in the coating composition to improve the appearance of the coating film formed after curing of the coating composition. In some embodiments, the pigment can comprise a colored pigment and / or an extender pigment. The colored pigment can be an inorganic colored pigment, an organic colored pigment, and / or a naturally occurring colored pigment. Examples of inorganic colored pigments include titanium dioxide (Ti02), iron oxide, chromium oxide (Cr203), and cobalt. Examples of organic colored pigments include azo pigments, quinacridone pigments, dioxazine pigments, and anthraquinone pigments. Examples of naturally occurring colored pigments include ocher, indigo, and chlorophyll. Examples of extender pigments include calcium carbonate (CaC03), talc (Mg3Si4O10(OH)2), barium sulfate (BaS04), mica, and zinc oxide (ZnO). In some embodiments, the pigment is present in an amount of about 1.0 wt% to about 30 wt%, or about 5.0 wt% to about 25 wt%, or about 10 wt% to about 20 wt%, based on the total weight of the coating composition. 10 (OH)2), barium sulfate (BaS04), mica, and zinc oxide (ZnO). In some embodiments, the pigment is present in an amount of about 1.0 wt% to about 30 wt%, or about 5.0 wt% to about 25 wt%, or about 10 wt% to about 20 wt%, based on the total weight of the coating composition.

[0037] In some embodiments, the coating composition can further comprise other additives different from the inorganic particulate component, the wax powder, and the pigment. These additives can include rheological additives, pigment dispersants, antioxidants, ultraviolet absorbers, light stabilizers, leveling agents, defoamers, and adhesion promoters, provided that these additives do not overlap with the categories of the components described above. If a certain component is to the extent that it satisfies the filler package requirement, that component is considered as part of the filler package, rather than as a separate additive.

[0038] In some embodiments, the coating composition has a dynamic viscosity of no more than about 150 cPs, as determined at 24 °C using a Brookfield viscometer at 100 rpm using a #2 LV spindle at 50% total solids. The dynamic viscosity value described is believed to be desirable flow properties of the coating composition to make it easy to apply to a substrate using existing application methods, such as spraying or brushing.

[0039] The composite articles provided herein include a substrate and a film formed from the coating compositions described herein. The substrate can include wood, plastic, metal, and / or other materials. The substrate can be multi-layered and can include other coatings, provided that the film formed from the coating compositions described herein is the display face or outermost layer of the article. The substrate can be a household item, an automotive part, or an industrial machinery part. In some embodiments, the substrate can be a piece of household furniture, such as a door, a drawer, a cabinet, a leg, a seat, a table, or a kick panel, particularly an article that can be subject to wear during use.

[0040] The film is included in the composite article to improve one or more properties of the substrate, such as appearance, strength, or chemical resistance. In some embodiments, the film includes a substantially crosslinked thermoset polymer formed from the reaction of a hydroxyl-functional resin with a crosslinker, optionally in the presence of heat and / or an acid catalyst.

[0041] In some embodiments, the composite article has a wear resistance such that no marks are present on the surface of the composite article based on visual observation at a distance of three feet from the composite article in a room under standard lighting, and the change in gloss value measured according to ASTM D523-12 using a gloss meter at a 60 degree angle is less than 5 gloss points after a 521 cycle test of the composite article using a heavy duty linear abrasion machine equipped with a 1000 mesh scouring pad as the test media under the application of a 2200 gram weight.

[0042] The methods provided herein are directed to forming the composite articles described herein. The methods include applying the coating compositions described herein to a substrate to form a film and curing the film. Applying the coating composition to the substrate can include applying by existing methods such as spraying, brushing, or rolling. The ability to apply by a spraying method and the wear resistance of the film after curing of the coating composition are unique advantages of the coating compositions described herein. The coating composition can be applied to the substrate manually by hand or automatically by machine. In embodiments where the coating composition is a one-component (lk) composition, the coating composition can be applied directly to the substrate without a mixing step. In embodiments where the coating composition is a two-component (2k) composition, the methods can further include combining and / or mixing the two separate components together before applying the resulting coating composition to the substrate.

[0043] The cured film can include applying heat to the film. For example, the film can be exposed to a temperature of about 50 °C to about 100 °C for about 4 minutes to about 10 minutes, or the film can be exposed to a temperature of about 25 °C to about 50 °C for about 45 minutes to about 75 minutes. The curing of the coating composition causes the hydroxyl functional resin to react with the crosslinker, which causes the coating composition to transition from a flowable material to a substantially crosslinked thermoset material.

[0044] Examples

[0045] Examples 1-4

[0046] Four coating compositions were prepared as shown in Table 1 below. The coating compositions of Examples 1-3 were comparative examples not in accordance with the present disclosure. The coating composition of Example 4 was a coating composition in accordance with the present disclosure.

[0047] Table 1: Coating Composition Contents

[0048]

[0049] In Table 1, the percentages represent the weight percent of each ingredient based on the total weight of the respective coating composition.

[0050] Resin A was a blend of an acrylic resin having a weight average molecular weight of about 6,000 Daltons to about 30,000 Daltons, a glass transition temperature (Tg) of about 10 °C to about 60 °C, and an OH value of about 50 mg KOH / g to about 150 mg KOH / g, available from Axalta Coating Systems Ltd., and an alkyd resin having an OH value of about 140 mg KOH / g to about 190 mg KOH / g, available from Polimeros Sinteticos, S.A. de C.V.

[0051] Crosslinker A was an alkylated melamine crosslinker having an equivalent weight of about 75 grams / equivalent, available from Allnex GMBH.

[0052] Solvent A was a blend of solvents including isobutyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, butanol, isobutyl alcohol, isopropyl alcohol, ethanol, methyl amyl ketone, methyl ethyl ketone, xylene, and toluene.

[0053] Acid catalyst A was a sulfonic acid catalyst, available from Allnex GMBH.

[0054] The inorganic particulate component A is 3M Ceramic Microspheres, which is an aluminum silicate inorganic particulate component having a D90 nominal size of 12 microns (determined using a sieve according to ASTM 5861-07 (2017)), a hardness value on the Mohs scale of hardness of 6.

[0055] The wax powder A is a polyethylene wax powder, commercially available from Micro Powders, Inc., having a softening point of 150 to 180 °C, an average nominal particle size of 10-25 microns, determined using a sieve according to ASTM 5861-07 (2017).

[0056] The pigment A is a blend of titanium dioxide and talc.

[0057] The additive A is a polyether-modified polymethylsiloxane and cellulose acetate butyrate.

[0058] The flow of each coating composition was tested. The dynamic viscosity of the coating compositions was determined at 24 °C using a Brookfield viscometer at 100 rpm using a #2 LV spindle at 50% total solids.

[0059] Each coating composition was then applied to a kitchen cabinet door and cured at 65 °C for 5 minutes to form a composite article corresponding to each coating composition. Each composite article was subjected to abrasion resistance, adhesion, and yellowing tests as described below. The results are shown in Table 2 below.

[0060] The abrasion resistance of the cured coating was determined using a Taber Heavy Duty Linear Abraser Model 5800 with a blue Scotch Brite pad (1000 grit scouring pad) as the test media. The linear abraser was run for 521 cycles with a 2200 gram weight applied. The composite article was then visually observed at a distance of three feet from the composite article in a room under standard lighting and the gloss was determined using a gloss meter according to ASTM D523-14 method at a 60 degree angle. The adhesion of the cured coating to the substrate was determined by the crosshatch / tape pull method as described in ASTM 3359. The yellowing of the cured coating was determined by a color spectrophotometer Datacolor 800 using the method described by ASTM G154.

[0061]

[0062] In Table 1, a rating of 1 indicates performance is far below customer requirements. A rating of 2 indicates performance does not meet customer requirements but is better than a rating of 1. A rating of 3 indicates performance meets or exceeds customer requirements. Specifically, a flow rating of 1 indicates the dynamic viscosity of the coating composition is in the range of about 150 cPs to about 400 cPs and the coating composition cannot be sprayed using a Kremlin AVX 12-174 tip or equivalent equipment. A flow rating of 2 indicates the dynamic viscosity of the coating composition is in the range of about 150 cPs to about 200 cPs and the coating composition cannot be sprayed using a Kremlin AVX 12-174 tip or equivalent equipment. A flow rating of 3 indicates the dynamic viscosity of the coating composition is in the range of about 50 cPs to about 150 cPs and the coating composition can be sprayed using a Kremlin AVX 12-174 tip or equivalent equipment. A mar rating of 1 indicates the measured gloss value experiences a change of greater than 10 gloss points. A mar rating of 2 indicates the measured gloss value experiences a change of greater than 5 gloss points. A mar rating of 3 indicates no marks are present on the surface of the composite article based on visual observation at a distance of three feet in a room under standard lighting and the measured gloss value experiences a change of less than 5 gloss points. An adhesion rating of 1 indicates the crosshatch rating is between 1B and 2B. An adhesion rating of 2 indicates the crosshatch rating is between 2B and less than 4B. An adhesion rating of 3 indicates the crosshatch rating is greater than or equal to 4B. A yellowing rating of 1 indicates the CIELAB dB color change change is greater than 0.70. A yellowing rating of 2 indicates the CIELAB dB color change change is greater than 0.40. A yellowing rating of 3 indicates the CIELAB dB color change change is less than 0.40.

[0063] The results of Examples 1-4 indicate that the composition containing only both the inorganic particulate component (3M Ceramic Microspheres) and the wax powder (polyethylene wax) (Example 4) meets customer requirements in all categories. The composition containing neither the wax powder nor the inorganic particulate component (Comparative Example 1) has a mar resistance far below customer requirements. The composition containing the wax powder but not the inorganic particulate component (Comparative Example 2) still does not meet customer requirements for mar resistance. The composition containing the inorganic particulate component but not the wax powder (Comparative Example 3) meets customer requirements for mar resistance but has poor flow. The results indicate an unexpected synergy between the inorganic particulate component and the wax powder when combined with the hydroxyl-functional resin, crosslinker, and solvent.

[0064] While at least one exemplary embodiment has been presented in the foregoing detailed description of the application, it should be appreciated that a vast number of modifications can be made to the exemplary embodiments without departing from the scope of the present disclosure. Additionally, it should be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the disclosure. It should be understood that various changes can be made in the function and arrangement of elements described in the exemplary embodiments without departing from the scope of the disclosure as set forth in the appended claims.

Claims

1. A coating composition comprising: a hydroxyl-functional resin having a plurality of free hydroxyl groups; a crosslinker having hydroxyl-reactive functional groups; a solvent; an inorganic particulate component having a D90 nominal particle size of about 12 microns to about 22 microns as determined using a sieve according to ASTM 5861-07 (2017); and a wax powder.

2. The coating composition of claim 1, wherein the inorganic particulate component has a hardness value on the Mohs hardness scale of about 4 to about 8.

3. The coating composition of claim 1, wherein the inorganic particulate component comprises metal silicate particles.

4. The coating composition of claim 3, wherein the metal silicate particles comprise aluminum silicate, magnesium silicate, zirconium silicate, or a combination thereof.

5. The coating composition of claim 1, wherein the inorganic particulate component is present in an amount of about 0.5 wt% to about 4.0 wt% based on the total weight of the coating composition.

6. The coating composition of claim 1, wherein the wax powder has an average nominal particle size of about 10 microns to about 25 microns as determined using a sieve according to ASTM 5861-07 (2017).

7. The coating composition of claim 1, wherein the wax powder has a softening point of about 150 °C to about 180 °C.

8. The coating composition of claim 1, wherein the wax powder comprises polyethylene, polypropylene, polyamide, polytetrafluoroethylene, or a combination thereof.

9. The coating composition of claim 1, wherein the wax powder is present in an amount of about 0.5 wt% to about 4.0 wt% based on the total weight of the coating composition.

10. The coating composition of claim 1, further comprising an acid catalyst.

11. The coating composition of claim 10, wherein the acid catalyst comprises a sulfonic acid, a phosphoric acid, a benzoic acid, or a combination thereof.

12. The coating composition of claim 1, further comprising a pigment having a hardness and / or particle size different from the hardness and / or particle size of the inorganic particulate component.

13. The coating composition of claim 1, having a dynamic viscosity of no more than about 150 cPs as determined at 24 °C using a Brookfield viscometer at 100 rpm using a number 2 LV spindle at 50% total solids.

14. The coating composition of claim 1, wherein the hydroxyl-functional resin comprises an acrylic type resin, an alkyd resin, a polyester resin, a hydroxyl-functional polyepoxy resin, a polyester urea resin, a urea formaldehyde resin, or a combination thereof.

15. The coating composition of claim 1, wherein the crosslinker is selected from the group consisting of a polyisocyanate, a blocked polyisocyanate, a melamine, a melamine derivative, a benzoguanamine, a silane, an epoxide, and combinations thereof.

16. A composite article comprising: a substrate; and a film formed from the coating composition of claim 1.

17. The composite article of claim 16 having an abrasion resistance such that no marks are present on the surface of the composite article based on visual observation at a distance of three feet from the composite article in a room under standard lighting and a change in gloss value of less than 5 gloss points as measured according to ASTM D523-12 using a gloss meter at a 60 degree angle after a 521 cycle test of the composite article using a heavy duty linear abrasion machine equipped with a 1000 mesh scouring pad as the test media under the application of a 2200 gram weight.

18. The composite article of claim 16, wherein the film comprises a substantially crosslinked thermoset polymer formed from the reaction of a hydroxyl functional resin and a crosslinker.

19. A method of forming a composite article comprising: applying the coating composition of claim 1 to a substrate to form a film; and curing the film.

20. A filler package for a coating composition comprising: an inorganic particulate component having a hardness value on the Mohs hardness scale of from about 4 to about 8 and a D90 nominal particle size of from about 12 microns to about 22 microns as measured according to ASTM 5861-07 (2017) using a screen mesh; and a wax powder having a softening point of from about 150 °C to about 180 °C and an average nominal particle size of from about 20 microns to about 25 microns as measured according to ASTM 5861-07 (2017) using a screen mesh.

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